This invention relates to the field of locking devices. More particularly, this invention relates to the field of computerized locking devices having passwords. Still more particularly, this invention relates to computerized locking devices as they pertain to use with computerized electrical devices or appliances, particularly microwave ovens.
All microwave ovens incorporate mechanical or electrical safety interlock devices that prevent microwaves from being generated whenever the door of the oven is open. These interlock devices are intended to protect people (both adults and children), animals and other objects near the microwave oven from being exposed to harmful microwave energy in the event that the oven's door is accidentally opened while the microwave oven is in operation.
Nowadays, operation of a microwave oven is so simple that even a young child can operate one. Unfortunately, no safety interlock exists that would prevent a child from microwaving a toy or other item out of curiosity or as part of a "pretend" activity. This invention is intended to provide protection against such an activity. One can imagine dangerous situations arising when children, under the age of about seven, the age at which abstract reasoning capabilities begin to emerge, cause a microwave oven to operate without knowing which objects are microwave safe. These dangerous situations can occur when a child operates any electrical appliance. In the case of microwave ovens, manufacturers have left children, and households with children, only one button away from a catastrophe.
Typical of the dangerous scenarios that this invention is intended to prevent is a situation in which a young girl wakes up early on a cold winter morning and finds that her doll has fallen on the floor during the night. When she retrieves it, it is very cold. She has an association that, when something is cold, like milk, and one wants it to be warm, one puts it into the microwave oven and presses the buttons. The young girl then places the doll in the microwave oven and mimics the button-pressing motions that she has seen her parents perform many times before. When the oven starts operating, the plastic materials of the doll may melt and begin to burn, and any metallic parts may give off sparks and set fire to the doll's clothing. The child may be near enough to inhale toxic fumes or may be burned or have her pajamas set on fire.
Among the existing forms of safety interlock that would have prevented such a scenario are the physical lock and key method and the preset password method. The lock and key method has been used quite effectively in many fields as a way of preventing unauthorized persons, i.e., those who do not physically possess a copy of the key, from gaining access to the device that is locked. Similarly, the use of "passwords," including numerical sequences, as a safety or security device has been a common part of society ever since the original "Open Sesame." Most mechanized or computerized embodiments, ranging from numerically operated door locks to automatic teller machines, use preset passwords. In addition, all existing password embodiments keep the password hidden from casual view. These typical approaches are thought to be effective because a child would need to physically unlock a microwave oven using a key or would need to press a particular preset sequence of buttons in order to operate the microwave oven.
However, neither of the above approaches is suitable for use in controlling access by children to a microwave oven. The lock and key method has proven to be much too inconvenient to assure continued safety because the physical key is likely to be lost or permanently inserted into the lock, and thus rendered unusable to others. Also, the child may fiend the key and may even be able to open the lock, thus thwarting the safety interlock feature. Similarly, the preset password approach also proves to be inconvenient because it requires the adult to set and then remember the password; should the password be forgotten, however, the user will be unable to operate the microwave oven until a new password is set. Also, the password may inadvertently be divulged to children, as when friends and neighbors drop in and use the microwave oven, and the password is called out loud to them ("Oh yeah. Hit one, two, three, start!"). And, because children learn their numbers at a very young age, children hearing this sequence of numbers will easily learn the password. For these reasons, neither of these approaches is satisfactory.
It is, therefore, one object of this invention to provide a child-proof safety interlock system for a microwave oven.
It is also an object of this invention to provide a safety interlock system for a microwave oven using a variable password.
It is a further object of this invention to provide a safety interlock system for a microwave oven using a variable password that is dynamically generated by the user just prior to each use.
It is still a further object of this invention to provide a safety interlock system for a microwave oven using a variable password that is always in plain view to the user so that the user does not have to remember it.
It is yet another object of this invention to provide a child-proof safety interlock system for any electrical device or appliance that can be dangerous when used by children.
These and other objects of the invention will become more apparent from the discussion below.